During transmission of information from a sender to a receiver, there are basically tour aspects that need to be fulfilled for obtaining a secure transmission, viz.
authenticity, i.e. that the sender and receiver are the purported sender and receiver;
integrity, i.e. that the information has not been altered during the transmission;
confidentiality, i.e. that the information is kept secret during the transmission; and
non-repudiation, i.e. that the information cannot be denied by either party.
These four aspects can be met by using cryptography.